So i have here my codes for fetching informations from the database using
the listview, and now i want to use the datagridview but i dont know how
to do it using the ADODB Connectionenter image description here.
If you are able to use an Odbc connection instead try this to retreive your data
Dim conn As New OleDb.OleDbConnection("path to your database")
Dim cmd As New OleDb.OleDbCommand
Dim da As New OleDb.OleDbDataAdapter
Dim sql as String
Sql = "your SQL Query"
conn.Open()
cmd.Connection = conn
cmd.CommandText = Sql
da.SelectCommand = cmd
You can try using Odbc Connection in VB.Net.
First add new Module named Connection.vb
Imports System.Data.Odbc
Module Connection
Public Con As New OdbcConnection
Public Adpt As New OdbcDataAdapter
Public Ds As New DataSet
Public Cmd As OdbcCommand
Public Read As OdbcDataReader
Public Sql As String
Public StrCon As String = "Dsn=Your DSN Name in Odbc Connector"
Public Sub Connect()
Con = New OdbcConnection(StrCon)
If Con.State <> ConnectionState.Closed Then Con.Close()
Con.Open()
End Sub
End Module
And next don't forget to add Imports System.Data.Odbc in every form you have to connect to your Odbc Connection.
Simple Code to add item on ComboBox from Database.
Call Connect()
Cmd = New OdbcCommand("SELECT * FROM `category` ", Con)
cmbKategori.Items.Clear()
cmbKategori.AutoCompleteCustomSource.Clear()
Read = Cmd.ExecuteReader()
If Read.HasRows = True Then
While Read.Read()
cmbKategori.AutoCompleteCustomSource.Add(Read("name_category"))
cmbKategori.Items.Add(Read("name_category"))
End While
End If
Related
When I try to connect to AcessDB, I get the error
"Keyword is not supported: provider".
When I try to change provider, I get another error. When I delete provider tag, I also get an error.
Dim Exists As Boolean = False
Dim ConnectionString As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\Name\Documents\Visual Studio 2010\Projects\datagrid\datagrid\pokus.accdb;Persist Security Info=False;"
Dim connection As New SqlConnection(ConnectionString)
Try
connection.Open()
Dim command As SqlCommand = connection.CreateCommand
command.CommandText = "SELECT * FROM studenti"
Dim reader As SqlDataReader = command.ExecuteReader
If reader.HasRows Then
Exists = True
Else
Exists = False
End If
reader.Close()
command.Dispose()
Catch ex As Exception
Console.Write(ex.Message)
Finally
connection.Close()
End Try
SqlConnection, SqlCommand, etc. are SQL Server-specific classes. You can't use them to connect to MS Access.
The documentation for SqlConnection makes this very clear:
Represents an open connection to a SQL Server database.
Consider using the OldDbConnection and related classes instead.
I always write wrapper classes for database connections, and I always recommend the same.
Dim sConnectionString As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\Name\Documents\Visual Studio 2010\Projects\datagrid\datagrid\pokus.accdb;Persist Security Info=False;"
Dim Conn As New OleDbConnection
Conn.ConnectionString = sConnectionString
Conn.Open()
Dim sQuery As String = "SELECT * FROM studenti"
Dim da As New OleDbDataAdapter(sQuery, Conn)
Dim dt As New DataTable
da.Fill(dt)
Conn.Close()
I am using an OledbConnection to an AS400 computer. When I have a SQL statement that will return nothing, it just hangs on the adapter command Fill.
Function ExecuteOLEDBQuery(ByVal cmdtext As String) As DataTable
Try
Dim connString As String = "Provider=IBMDA400;Persist Security Info=True;User ID=##USERID;Password=##PASSWORD;Data Source=##SYSTEM"
Dim as400 As New OleDb.OleDbConnection(connString)
Dim cmd As New OleDb.OleDbCommand(cmdtext, as400)
Dim adapter As New OleDb.OleDbDataAdapter(cmd)
cmd.CommandTimeout = 60 'Doesn't work. It never times out.
Dim dt As New DataTable
as400.Open()
adapter.Fill(dt) 'This is where it hangs
as400.Close()
adapter.Dispose()
cmd.Dispose()
Return dt
Catch ex As Exception
Return Nothing
End Try
End Function
Any ideas?
It may be the connection to the AS400 itself. Try this version which disposes of the object in a slightly different order:
Function ExecuteOLEDBQuery(cmdtext As String) As DataTable
Using cn = New OleDbConnection("Provider=IBMDA400;Persist Security Info=True;User ID=##USERID;Password=##PASSWORD;Data Source=##SYSTEM")
cn.Open()
Using da = New OleDbDataAdapter(cmdtext, cn)
Dim dt = New DataTable
da.Fill(dt)
Return dt
End Using
End Using
End Function
I am trying to figure out why I am getting an error of 'Object reference not set to an instance of an object.' when my winforms code runs. I have set a breakpoint on the sql statement and stepped into the code and it shows as the line: Using dr = oledbCmd.ExecuteReader()
I am still learning vb.Net so would appreciate some help as to how to overcome this error. Many thanks
DBConnection.connect()
sql = "SELECT * from Boxes WHERE Customer = ? AND Status = 'I'"
Dim cmd As New OleDb.OleDbCommand
cmd.Parameters.AddWithValue("#p1", cmbCustomer.Text)
cmd.CommandText = sql
cmd.Connection = oledbCnn
dr = cmd.ExecuteReader
Using dr = oledbCmd.ExecuteReader()
While dr.Read()
Dim LV As New ListViewItem
With LV
.UseItemStyleForSubItems = False
.Text = dr(1).ToString()
.SubItems.Add(dr(2).ToString())
End With
lvSelectRequestItems.Items.Add(LV)
End While
End Using
cmd.Dispose()
dr.Close()
oledbCnn.Close()
DBConnect module
Imports System.Data.OleDb
Module DBConnection
Public connetionString As String = My.Settings.storageConnectionString
Public oledbCnn As New OleDbConnection
Public oledbCmd As OleDbCommand
Public dr As OleDbDataReader
Public sql As String
Sub connect()
'connetionString = My.Settings.storageConnectionString
oledbCnn.ConnectionString = connetionString
oledbCnn.Open()
End Sub
End Module
I saw several mistakes. Look to the comments for reasons for the changes
Dim sql As String = "SELECT * from Boxes WHERE Customer = ? AND Status = 'I'"
'.Net uses connection pooling, such that you're better using a new connection object for each query
'Also, a Using block will ensure the connection is closed, **even if an exception is thrown**
' The original code would leak connections when exceptions occured, eventually locking you out of the db
Using cn As New OleDb.OleDbConnection("Connection string here"), _
cmd As New OleDb.OleDbCommand(sql, cn) 'set CommandText BEFORE adding parameters
'Use explicit parameter types
cmd.Parameters.Add("?", SqlDbType.NVarChar, 50).Value = cmbCustomer.Text
cn.Open()
Using dr As OleDb.OleDbDataReader = cmd.ExecuteReader()
While dr.Read()
Dim LV As New ListViewItem
With LV
.UseItemStyleForSubItems = False
.Text = dr(1).ToString()
.SubItems.Add(dr(2).ToString())
End With
lvSelectRequestItems.Items.Add(LV)
End While
dr.Close()
End Using
End Using
You have failed to properly bind the SqlConnection to the SqlCommand object.
Using connection As New SqlConnection(connectionString)
connection.Open()
Dim command As New SqlCommand(queryString, connection)
Dim reader As SqlDataReader = command.ExecuteReader()
While reader.Read()
Console.WriteLine("{0}", reader(0))
End While
End Using
See: MSDN
Edit: Requested adjustment to aid in clarity:
Using connection As New Data.SqlClient.SqlConnection
Dim sql As String = "SELECT * from Boxes WHERE Customer = ? AND Status = 'I'"
connection.Open()
Using command As New Data.SqlClient.SqlCommand(Sql, connection)
command.Parameters.AddWithValue("#p1", cmbCustomer.Text)
dr = command.ExecuteReader()
While dr.Read()
Dim LV As New ListViewItem
With LV
.UseItemStyleForSubItems = False
MediaTypeNames.Text = dr(1).ToString()
.SubItems.Add(dr(2).ToString())
End With
lvSelectRequestItems.Items.Add(LV)
End While
End Using
End Using
Your code should look something like that.
you have a fair amount of potential issues going on here.
1-you are using your dr variable twice. once before the using, which is probably causing your error. then again in for using, which does not look right because it is not the cmd variable used to execute the reader. so change this part of your code:
cmd.CommandText = sql
cmd.Connection = oledbCnn
dr = cmd.ExecuteReader
Using dr = oledbCmd.ExecuteReader()
to this:
cmd.CommandText = sql
cmd.Connection = oledbCnn
Using dr = cmd.ExecuteReader()
2-you are not showing if oledbCnn has been opened yet. I'm assuming your DBConnection.connect() function is doing this and olebCnn is a variable that function sets and opens
3-I'm not sure if the question mark in your query string will work. Even if it does you should replace it with the parameter name. so your query string should be:
sql = "SELECT * from Boxes WHERE Customer = #p1 AND Status = 'I'"
lastly you should probably show all the code for the sub(or function) this is for so we can get a full picture. example dr must be declared before the using else you would get a build error.
I am writing a windows service that will read records from one table and write them to another table. Problem is when i declare cmd = New SqlCommand(l_sSQL) the code stop executing
but the service will still be running. I can insert into the other table using the service but i cant read from the other table.
Code Sample:
Private Sub dbcon()
Dim con As New SqlConnection
Dim cmd As New SqlCommand
Dim adapter As New SqlDataAdapter
Dim ds As New DataSet
Dim x As String
Try
con.ConnectionString = "Data Source=xxxx;Initial Catalog=xxxxx;Persist Security Info=True;User ID=sa;Password=xxxxxxx"
con.Open()
cmd.Connection = con
cmd = New SqlCommand()
Dim i As Integer
l_sSQL = "SELECT * ozekimessageout"
cmd = New SqlCommand(l_sSQL)\\stops executing here
adapter.SelectCommand = cmd
adapter.Fill(ds)
For i = 0 To ds.Tables(0).Rows.Count - 1
x = (ds.Tables(0).Rows(i).Item(1))
next
End Sub
Please Help....
Don't you need: SELECT * FROM ozekimessageout
Plus: You are 'newing' cmd twice, there is no need.
I've managed to get the following code...
con.ConnectionString = My.Settings.dbConnection
Dim sqlCmd As System.Data.OleDb.OleDbCommand = New System.Data.OleDb.OleDbCommand()
con.Open()
sqlCmd.Connection = con
Dim schemaTable As DataTable
schemaTable = con.GetOleDbSchemaTable(System.Data.OleDb.OleDbSchemaGuid.Views, Nothing)
To retrieve a list of Views in my Access database, but now I want to retrieve the results based on a selected View.
Is there a correct method in doing this, or do I take the SQL Statement from the DataTable returned for each row?
Suppose you have Query1 (View) in your Access database (Database1.accdb file). The following code will output each row of the query to the console (for demo purposes):
Dim con As OleDbConnection = New OleDbConnection()
con.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Database1.accdb;Persist Security Info=False;"
Dim sqlCmd As OleDbCommand = New System.Data.OleDb.OleDbCommand()
sqlCmd.CommandType = CommandType.StoredProcedure
sqlCmd.CommandText = "Query1"
sqlCmd.Connection = con
con.Open()
Dim reader As OleDbDataReader
reader = sqlCmd.ExecuteReader()
If reader.HasRows Then
While reader.Read()
Console.WriteLine(reader("Column1")) 'output specific column
End While
End If
Console.ReadLine()
Hope this helps